Ketimines of benzylated polyamines as curing agents

ABSTRACT

Ketimines of benzylated polyamines and MEK are disclosed. The ketimines can be used as an epoxy curing agent and impart improved potlife, and enhanced blush and chemical resistance of cured epoxy coatings.

This Application claims the benefit of Application No. 62/053,370, filedon Sep. 22, 2014. The disclosure of Application No. 62/053,370 is herebyincorporated by reference.

FIELD OF THE INVENTION

This invention relates to ketimines based on benzylated polyamines andmethyl ethyl ketone (MEK) and methods for making and using the ketiminesas epoxy curing agents.

BACKGROUND OF THE INVENTION

Ketimines are known as latent curing agents for many applications andare especially useful in moisture rich environments however; epoxysystems using ketimines based on aliphatic amines have poor chemicalresistance and are prone to whitening or blushing. Benzylated polyamineshave been shown to provide chemical resistance and reduce blushing buttheir reactivity can lead to short potlife when used as an epoxy curingagent.

U.S. 2005/0010022A1 discloses a curing agent containing a ketimine.Patent Applications disclosing benzylated polyamines as curing agentsinclude U.S. 2013/0079435A1, U.S. 2009/0163676A, U.S. 2009/0030125 andU.S. 2009/0023846A1 with benzylated polyamines described as having atleast three nitrogen atoms, at least three active amine hydrogen atomsand at least one benzyl group. JP111524434A describes the use ofketimine made with a combination of MEK and methyl isobutyl ketone.

U.S. Pat. No. 6,573,357 describes a process for the production ofaliphatic ketimines using a decanter to separate water from ketone.

The disclosure of the previously identified patents and patentapplications is hereby incorporated by reference.

BRIEF SUMMARY OF THE INVENTION

The instant invention solves problems associated with conventionalketimines by providing ketimines of benzylated polyamines and MEK.Ketimines of the present invention provide improved potlife, blush andchemical resistance at ambient, elevated or low temperatures. By“improved potlife” it is meant the inventive ketimine have a workingtime that is longer than the benzylated polyamines. By “improved blushand chemical resistance” it is meant that an epoxy resin cured with theinventive ketimines will not have amines migrating to the coatingssurface and also that the inventive ketimines provides chemicalresistance against some chemical agents where conventional ketiminiestypically fails. By “cured” it is meant that the inventive ketimine willproperly react with the epoxy resin at ambient or low temperature.

One aspect of the invention relates to a compound comprising a ketimineof benzylated polyamines.

Another aspect of the invention relates to a method for making aketimine of benzylated polyamines comprising contacting at least oneketone with at least one benzylated polyamine.

Another aspect of the invention to relates to any of the foregoingaspects wherein the ketone comprises MEK.

A further aspect of the invention relates to any of the foregoingaspects wherein the contacting employs the following formula:

Wherein R1 is benzyl, R2 is H, alkyl, cycloaliphatic or benzyl, R3 andR4 are (CH₂)_(m) provided that m=2-6; n=1-3; and R5 and R6 are C1-C10linear or branched aliphatic or cycloaliphatic or substitutedcycloaliphatic hydrocarbon or aromatic hydrocarbon, and R7 is H orC3-C10 containing linear or branched aliphatic or cycloaliphatic orsubstituted cycloaliphatic hydrocarbon or aromatic hydrocarbon orhydroxyl.

One aspect of the invention relates to a composition comprising at leastone ketimine of benzlyated polyamines.

Another aspect of the invention relates to an epoxy curing agentcomprising at least one ketimine of benzylated polyamines.

A further aspect of the invention relates to the foregoing aspects andfurther comprising at least one member selected from the groupconsisting of modified amines, like, aliphatic amine adducts,cycloaliphatic amine adducts, unmodified cycloaliphatic amine, MannichBase, Phenalkamines, Polyamides and Amidoamines.

One aspect of the invention relates to a composition comprising at leastone ketimine of benzylated polyamines and at least one epoxy resin.

The various aspects of the invention can be used alone or in variouscombinations.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to ketimines based on benzylatedpolyamines and methyl ethyl ketone, and methods for making the ketiminesand methods for using the ketimines as epoxy curing agents.

Ketimines of the instant invention can be produced by any suitablemethod. In one aspect of the invention, the inventive ketimines are aproduct of benzylated polyamines and ketones with the following formula:

R1 benzyl, R2 and can be H, alkyl, cycloaliphatic or benzyl, R3 and R4(CH₂)_(m) m=2-6 preferred m=2 or 3 and n=1-3 Preferred n=1-2, R5, R6C1-C10 linear or branched aliphatic or cycloaliphatic or substitutedcycloaliphatic hydrocarbon or aromatic hydrocarbon. R7 is H or C3-C10containing linear or branched aliphatic or cycloaliphatic or substitutedcycloaliphatic hydrocarbon or aromatic hydrocarbon or hydroxyl.Preferred R5, R6=C1-C4.

Ketone to benzylated polyamine ratio used for making the inventivebenzylated polyamines can range from about 1:1 to about 10:1, about 1:1to about 5:1 and, in some cases, about 1:1 to about 1:1.5 equivalents ofketone to primary amine. The temperature can range from about 75 toabout 100, about 80 to about 95 and in some cases about 80 to about 90while using ambient pressure and a nitrogen blanket. The inventiveketimine can be produced using conventional equipment such as roundbottomed flask fitted with a nitrogen blanket, thermocouple and acondenser connected to a Dean-Stark trap.

Benzylated polyamines are defined as the reaction product of abenzaldehyde compound or benzyl halide compound with a polyalkylenepolyamine having at least three nitrogen atoms, at least three activeamine hydrogen atoms and at least one benzyl group. Examples ofbenzylated polyamines comprise at least one member selected from thegroup consisting of benzylated polyethylene polyamines, benzylatedpolypropylene polyamines, benzylated aminopropylated ethylenediaminesand benzylated aminopropylated propylenediamines and combinationsthereof.

Ketones can comprise at least one member selected from the groupconsisting of acetone, methyl ethyl ketone, methyl propyl ketone, methylisopropyl ketone, methyl butyl ketone, methyl isobutyl ketone, methyln-amyl ketone, methyl isoamyl ketone, methyl heptyl ketone, diethylketone, ethyl butyl ketone, ethyl amyl ketone, diisopropyl ketone,diisobutyl ketone, cyclohexanone, cyclopentanone, methyl cyclohexanone,isophorone, methyl t-butyl ketone, 5-methyl-3-heptanone, 4-heptylketone, 1-phenyl-2-propanone, acetophenone, methyl nonyl ketone, dinonylketone, 3,3,5 trimethyl cyclohexanone. Preferred ketones includeacetone, and methyl ethyl ketone.

Polyalkylene polyamine compounds that are useful in producing thebenzylated polyalkylene polyamine compounds of the present inventioncomprise at least one member selected from the group consisting ofpolyethylene polyamines, polypropylene polyamines, aminopropylatedethylenediamines and aminopropylated propylenediamines and combinationsthereof. Non-limiting examples of polyethylene polyamines includediethylenetriamine (DETA), triethylenetetramine (TETA),tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and otherhigher polyethylene polyamines. Suitable polypropylene polyaminesinclude,but are not limited to, dipropylenetriamine,tripropylenetetramine, and other higher polypropylene polyamines.Aminopropylated ethylenediamines and aminopropylated propylenediaminesinclude, but are not limited to, N-3-aminopropyl ethylenediamine (Am3);N,N′-bis(3-aminopropyl)ethylenediamine (Am4);N,N-bis(3-aminopropyl)ethylenediamine;N,N,N′-tris(3-aminopropyl)ethylenediamine (Am5);N,N,N′,N′-tetrakis(3-aminopropyl)ethylenediamine;N-3-aminopropyl-1,3-diaminopropane;N,N′-bis(3-aminopropyl)-1,3-diaminopropane;N,N-bis(3-aminopropyl)-1,3-diaminopropane;N,N,N′-tris(3-aminopropyl)-1,3-diaminopropane;N,N,N′,N′-tetrakis(3-aminopropyl)-1,3-diaminopropane; andaminopropylated higher alkylenediamines. Mixtures of APADA compounds canbe employed in the present invention. Processes for using thepolyalkylene polyamine for making benzylated polyalkylene polyamine aredisclosed in U.S. 2013/0079435A1, U.S. 2009/0163676A, U.S. 2009/0030125and U.S. 2009/0023846A1; hereby incorporated by reference.

It will be recognized by those skilled in the art that polyethylenepolyamines containing 4 or more nitrogens are generally availablecommercially as complex mixtures, most of which contain the same numberof nitrogens. Side products in these mixtures are often calledcongeners. For example, TETA contains not only linear TETA, but alsotris-aminoethylamine, N,N′-bisaminoethylpiperazine, and2-aminoethylaminoethylpiperazine.

In one aspect of the present invention, at least one polyalkylenepolyamine compound is DETA, TETA, TEPA, PEHA, dipropylenetriamine,tripropylenetetramine or any combination thereof.

In another aspect, the at least one polyalkylene polyamine compound isDETA, or TETA, or a mixture of DETA and TETA. Typical mixtures of DETAand TETA are I part by weight of DETA to about 0.1 to about 1.1 parts byweight of TETA. In this and other aspects of the present invention, themixtures of DETA and TETA can be I part by weight of DETA to about 0.1about 0.2, about 03, about 0.4, about 0.5, about 0.6, about 0.7, about0.8, about 0.9, about 1.0, or about 1.1 parts by weight of TETA. Forexample, DETA/TETA weight ratios of 70/30 and 50/50 are useful in thepresent invention.

The reaction of ketones with amines results in the generation of wateras a by-product. When using ketones with high water solubility, theamount of water generated can be such that water does not readilyseparate from the reaction mixture. By high water solubility it is meantketones containing less than 6 carbon atoms. Without wishing to be boundby any theory or explanation, it is believed that equilibrium with watercan be reached thereby inhibiting the ketimine formation reaction fromgoing to completion. The inventive method for making the inventiveketimines solves this problem by employing a co-solvent to separatewater from the ketone thereby providing the ability to drive thereaction to completion and to recycle the solvent/ketone mixture. Theratio of co-solvent to ketone can range from about 1:1 to about 10:1,about 1:1 to about 1:5 and in some cases about 1:1 to about 1:2.

While any suitable co-solvent can be employed, example of suitableco-solvents can include hydrocarbons such as at least one memberselected from the group consisting of pentane, hexane, heptane, octane,nonane, cyclohexane, acetonitrile, toluene, and xylene.

The inventive ketimine can have an amine equivalent weight (AEW) rangingfrom about 85 to about 91, about 86 to about 92 and in some cases about88 to about 94.

The inventive process for making the inventive ketimine can, in someaspects, be substantially free of methylisobutylketone. By“substantially free” it is meant that the inventive ketimie and theprocess for making the inventive ketimine contains less than about 5wt%, less than about 3wt. % and typically about 0wt % ofmethylisobutylketone.

The inventive ketimine can be employed as a curing agent for epoxyresins. Examples of epoxy resins that can be cured with the inventiveketimine comprise at least one member selected from the group consistingof Diglycidil Ether of Bisphenol A (DGEBPA) or Diglycidil Ether ofBisphenol F (DGEBPF) or Epoxy Novolac Resin. The ratio of ketimine toepoxy can range from about 5% to about 30%, about 5% to about 50% and,in some cases about 1% to about 90%. One aspect the invention relates tocurable composition comprising about 5% to about 100% of the inventiveketime, and about 10% to about 90% of epoxy resin.

In one aspect of the invention, the inventive ketimine is combined withanother curing agent comprising at least one member selected from thegroup consisting of modified amines, like, aliphatic amine adducts,cycloaliphatic amine adducts, unmodified cycloaliphatic amine, MannichBase, Phenalkamines, Polyamides or Amidoamines. The ratio of inventiveketimine to other curing agents can range from about 3% to about 90%,about 10% to about 80% and in some cases about 20% to about 70%. Oneaspect of the invention relates to a curing agent composition comprisingabout 5% to about 95% inventive ketime, and about 95% to about 5% of theforegoing amine curing agents.

The inventive curing agent can be combined with an epoxy resin by usingany suitable equipment and methods. Examples of suitable equipment andmethods comprise high speed mixer, cowles or hand-mix.

The inventive curing agent can be combined with Epoxy Novolac Resins, orany other Epoxy resin containing more than 2 oxyrane rings per moleculein order to produce cured epoxy coatings having a Tg that can range fromabout 50 C to about 120 C, about 55 C to about 100 C and in some casesabout 40 C to about 90 C. Cured epoxy coatings or films obtained byusing the inventive curing agent can have a gloss value ranging fromabout 5 to about 50, about 10 to about 70 and in some cases about 20 toabout 100; a tack and blush on a scale of 0-5 ranging from about 0 toabout 3; and dry times from about 1 hour to about 72 hours.

The following examples are provided to illustrate certain aspects of theinvention and do not limit the scope of the claims appended hereto.

EXAMPLES Example 1 Preparation of Inventive Ketimine with WaterInsoluble Ketone

Benzylated polyamine (250 g) was weighed into a round bottomed flaskfitted with a nitrogen blanket, thermocouple and a condenser connectedto a Dean-Stark trap. Methyl isobutyl ketone (MIBK) (289 g) was addedallowing the mixture to heat to 40 C. When addition was complete themixture was heated to reflux, water/MIBK collected in the trap, wherewater phase separated from MIBK and MIBK was returned to the reactionflask. When water collection stopped the condenser/trap was replaced bya distillation head and excess ketone were removed by distillation. Areaction product was analyzed using GC/MS and confirmed that ketiminewas formed.

Example 2 Preparation of Inventive Ketimine with Water Soluble Ketones

Benzylated polyamine (200 g) and heptane (85 g) were weighed into around bottomed flask fitted with a nitrogen blanket, thermocouple and acondenser connected to a Dean-Stark trap. Methyl ethyl ketone (MEK) (169g) was added allowing the mixture to heat to 35 C. When addition wascomplete the mixture was heated to reflux, water/MEK/heptane collectedin the trap, where water phase separated from MEK/heptane andMEK/heptane was returned to the reaction flask. When water collectionstopped the condenser/trap was replaced by a distillation head andexcess ketone and heptane were removed by distillation. Final productamine equivalent weight (AEW, defined as grams per N) value 90 wasdetermined by titration using perchloric acid. A reaction product wasanalyzed using GC/MS and confirmed that ketimine was formed.

Example 3 Comparative Example Using Water Soluble Ketones WithoutCo-Solvent

Benzylated polyamine (200 g) was weighed into a round bottomed flaskfitted with a nitrogen blanket, thermocouple and a condenser connectedto a Dean-Stark trap. Methyl ethyl ketone (169 g) was added allowing themixture to heat to 35 C. When addition was complete the mixture washeated to reflux. Water did not separate from MEK in the trap and had tobe removed by distillation with MEK. Final product had an AEW value of83 indicating a relatively low conversion in comparison to Example 2.

Example 4 Preparation and Testing of Coatings

A curable epoxy resin was prepared by mixing ketimine with commerciallyavailable diglycidyl ether of bisphenol A (epoxy equivalent weightapprox 190 Dow Epoxy Resin DER 331) in proportions listed in Table 1. Ahigh speed mixer was used for mixing at an 600 rpm.

TABLE 1 Formulations Raw Material 1 2 3 Ethylenediamine-MIBK Ketimine100 N,N′-1,2-Etanediylbis(1,3- 100 Propanediamine)-MIBK KetimineBenzylated Polyamine-MIBK Ketimine 100 (Inventive Ketimine) AHEW 55 5673.5 Phr with DER331 (EEW = 190) 29 29 39

Coatings were applied at 75 micron WFT (wet film thickness) using a Birdapplicator resulting dry film thickness was 65 to 70 microns. Films werecured at 5 C and 50% humidity for a period of 24 hours. Films wereevaluated for tack and blush on a scale of 0-5 where 0 designates noblush or tack and 5 designates severe blush or tack. Amine blush wasdetermined using The Elcometer 139 Amine Blush Kit. Dry times weremeasured using a BK recorder in accordance with Test Method ASTM D-1640.Gloss was measured by ASTM D523. Tg was measured using a DSC inaccordance with Test Method ASTM E-1356.

TABLE 2 Coatings examples 1 2 3 Properties @ RT Film appearance onOpaque film due A lot of bubbles Continuous glass (visual) the manyinternal encapsulated Film bubbles. The in the film. film seemsExudation and some retract. little orange peel Blush after 24 hours 3-43-4 0-1 (scale: 0-5) Gloss 20°/60° 65/104 34/108 74/105 Tack after 24hours 5   0-1 0-1 (scale: 0-5) Tg after 9 days 42.38 41.4 44.36 Pot-life3 h 27 3 h 17 Drying time 16:00 02:50 01:30 (h:min) — 07:15 03:30 —09:00 06:00 — — —

A comparative example using ethylenediamine-MIBK andN,N′-1,2-Etanediylbis(1,3-Propanediamine)-MIBK exhibited a film withsuperficial defects that never fully cured with a high degree ofblushing. Benzylated polyamine-MIBK provided a continuous film that wastack and blush free with a thin film set time of 5 hours.

Example 5 Preparation and Testing of Coatings Produced with KetiminesUsing Alternative Ketones to Replace MIBK

A curable epoxy resin was prepared by mixing ketimine with commerciallyavailable diglycidyl ether of bisphenol A (epoxy equivalent weightapprox 190 Dow Epoxy Resin DER 331) in proportions listed in Table 3. Ahigh speed mixer was used for mixing.

TABLE 3 Coatings Formulations Methylene- Benzylated Methylene- biscyclo-Ethylene- polyamine/ Benzylated biscyclo- hexanamine, diamine/ MEKpolyamine/ hexanamine, 4,4′-/CYCLO- Ethylene- CYCLO- (Inventive CYCLO-Ketimine 4,4′-/MEK HEXANONE diamine/MEK HEXANONE Ketimine) HEXANONE AHEW79.50 92.50 42.10 55.10 76.50 85.30 EEW 190 190 190 190 190 190 phr withDER331 41.84 48.68 22.16 29.00 40.26 44.89 or similar (EEW = 190)

EEW is the Epoxy Equivalent Weight of the Epoxy resin used (Dow EpoxyResin DER331 or similar) and AHEW is the Amine Hydrogen EquivalentWeight.

The quantity of the Ketimine to react stoichiometric with 100 grams(phr) of the Epoxy Resin (DER331 or similar) mentioned on Table 3 wascalculated by the formula below:

${{phr} = {\frac{A\; H\; E\; W}{E\; E\; W} \times 100}};$

On the example with Benzylated polyamine/MEK Ketimine (The InventiveKetimine) 40,26 grams of the mentioned ketimine was used to react with100 grams of Diglycidil Ether of Bisphenol-A with (DER331 or similar) aEpoxy Equivalent Weight (EEW) of 190.

Coatings were applied at 75 micron WFT (wet film thickness) using a Birdapplicator resulting dry film thickness was 65 to 70 microns. Films werecured at 5 C and 50% humidity for a period of 24 hours. Films wereevaluated for tack and blush on a scale of 0-5 where 0 designates noblush or tack and 5 designates severe blush or tack. Amine blush wasdetermined using The Elcometer 139 Amine Blush Kit. Dry times weremeasured using a BK recorder in accordance with Test Method ASTM D-1640.Tg was measured using a DSC in accordance with Test Method ASTM E-1356.The results of the evaluations are listed in Table 4.

TABLE 4 Coatings Examples Benzylated Methylene- Benzylated polyamine/Methylene- biscyclo- Ethylene- polyamine/ CYCLO- biscyclo- hexanamine,diamine/ MEK HEXANONE hexanamine, 4,4′-/CYCLO- Ethylene- CYCLO-(Inventive (Inventive Ketimine 4,4′-/MEK HEXANONE diamine/MEK HEXANONEKetimine) Ketimine) Visual Continuous, Solid at Very DiscontinuousContinuous Continuous Appearance yellow and Ambient discontinuos and anduncured and cured and cured cured Temperature uncured film. It film.film film film presented tack even after 7 days Tack after 0 ** 5 2 0 024 hours (scale: 0-5) Blush after 0 ** 0 0 0 0 24 hours (scale: 0-5)Drying Stage 1 05:00 ** — 07:00 02:45 03:15 time Stage 2 08:15 ** — —03:45 05:15 (h:min) Stage 3 10:00 ** — — 05:00 06:45 Stage 4 13:15 ** —— 06:00 09:00

Comparing the data of formulation 1 from Table 2 (Ketimine formulatedwith Ethylenediamine and Methyl Isobutyl Ketone) and Table 4, each ofthe inventive ketimines formulated with Benzylated Polyamines providedcoating properties with faster drying times and completely eliminatedthe presence of amine blush and tack on the surface of the coating.

Example 6 Preparation and Testing of Coatings Produced by CombiningKetimines with Other Types of Amine Curing Agents

A curable epoxy resin was prepared by mixing the inventive ketimine withcommercially available diglycidyl ether of bisphenol A (epoxy equivalentweight approx 190 Dow Epoxy Resin DER 331) in proportions listed inTable 5. A high speed mixer was used for mixing.

TABLE 5 Coatings Formulations Raw Material 4 5 6 Ethylenediamine/MIBK 49Cycloaliphatic Amine (Ancamine 2167) 50 50 50 Imicure AMI-1 1 1 1Benzlated polyamine/MEK 49 Benzylated 49 polyamine/CYCLOHEXANONE AHEW54.52 63.13 65.88 EEW 190 190 190 Phr 28.69 33.23 34.68

Coatings were applied at 75 micron WFT (wet film thickness) using a Birdapplicator resulting dry film thickness was 65 to 70 microns. Films werecured at 5 C and 50% humidity for a period of 24 hours. Films wereevaluated for tack and blush on a scale of 0-5 where 0 designates noblush or tack and 5 designates severe blush or tack. Amine blush wasdetermined using The Elcometer 139 Amine Blush Kit. Dry times weremeasured using a BK recorder in accordance with Test Method ASTM D-1640.Tg was measured using a DSC in accordance with Test Method ASTM E-1356.The results of the evaluations are listed in Table 6.

TABLE 6 Coatings Examples Raw Material 4 5 6 Appearance Film with bigcrakers Continuous Film with (4 mm widht) Film spots Tack after 24 hours0-1 0 0 (scale: 0-5) Blush after 24 hours 5 1 0 (scale: 0-5) Drying time— — 02:45 (h:min) 00:15 03:00 04:45 — 07:30 09:00 20:45 — —

In the case of coatings formulated with Ketimine in combination withother amine curing agents, in this case more specifically withCycloaliphatic Amine (Ancamine 2167), the ketimine produced withBenzylated Polyamine and MEK provided a film having improved properties.

Example 6 Preparation and Testing of Coatings Produced by CombiningKetimines with Other Types of Amine Curing Agents

A curable epoxy resin was prepared by mixing ketimine with commerciallyavailable diglycidyl ether of bisphenol A (epoxy equivalent weightapprox 190 Dow Epoxy Resin DER 331) in proportions listed in Table 7. Ahigh speed mixer was used for mixing.

TABLE 7 Coatings Formulations Raw Material 7 8 9 10 Imicure AMI-1 1 1Benzylated polyamine/MEK 49 49 50 50 Cycloaliphatic Amine Adduct 40 40(Ancamine 2764) 1,2-Diaminocyclohaxane 10 Trimethyl hexametilene 10Diamine Mannich Base (Ancamine 25 2422) Modified Aliphatic Amine 25(Ancamine 2432) Benzyl Alcohol 25 25 AHEW 72.67 78.27 85.93 106.65 EEW190 190 190 190 Phr 38 41 45 56

Coatings were applied at 75 micron WFT (wet film thickness) using a Birdapplicator resulting dry film thickness was 65 to 70 microns. Films werecured at 5 C and 50% humidity for a period of 24 hours. Films wereevaluated for tack and blush on a scale of 0-5 where 0 designates noblush or tack and 5 designates severe blush or tack. Amine blush wasdetermined using The Elcometer 139 Amine Blush Kit. Dry times weremeasured using a BK recorder in accordance with Test Method ASTM D-1640.The results of the evaluations are listed in Table 8.

TABLE 8 Coatings Examples 7 8 9 10 Visual Continuous ContinuousContinuous Continuous Appearance film with film film film with someblush some blush Tack after 24 0 1 0 0 hours @ RT (scale: 0-5) Blushafter 24 0 0 0 2 hours @RT (scale: 0-5) Tack after 24 * 5 1 2 hours @ 5C. (scale: 0-5) Blush after 24 * 0 0 0 hours @5 C. (scale: 0-5) Dryingtime 02:00 01:30 02:00 03:00 (h:min) 03:15 02:45 03:45 05:15 05:30 03:3006:45 07:00 * * 10:15 11:00

In these Examples, the ketimine produced with Benzylated Polyamines andMEK demonstrates its applicability to obtain films with good visualappearance, even when the ketimine is combined with other curing agents.While the invention has been described with reference to certain aspectsor embodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt the teachings of theinvention without departing from the essential scope thereof. Therefore,it is intended that the invention not be limited to the particularembodiment disclosed as the best mode contemplated for carrying out thisinvention, but that the invention will include all embodiments fallingwithin the scope of the appended claims.

1) A compound comprising a ketimine of benzylated polyamines. 2) Amethod for making a ketimine of benzylated polyamines comprisingcontacting at least one ketone with at least one benzylated polyamine.3) The method of claim 2 wherein the ketone comprises MEK. 4) The methodof claim 2 wherein the contacting employs the following formula:

Wherein R1 is benzyl, R2 is H, alkyl, cycloaliphatic or benzyl R3 and R4are (CH₂), provided that m=2-6; n=1-3; and R5 and R6 are C1-C10 linearor branched aliphatic or cycloaliphatic or substituted cycloaliphatichydrocarbon or aromatic hydrocarbon, and R7 is H or C3-C10 containinglinear or branched aliphatic or cycloaliphatic or substitutedcycloaliphatic hydrocarbon or aromatic hydrocarbon or hydroxyl. 5) Acomposition comprising at least one ketimine of benzlyated polyamines.6) An epoxy curing agent comprising at least one ketimine of benzylatedpolyamines. 7) The epoxy curing agent of claim 3 further comprising atleast one member selected from the group consisting of modified amines,like, aliphatic amine adducts, cycloaliphatic amine adducts, unmodifiedcycloaliphatic amine, Mannich Base, Phenalkamines, Polyamides andAmidoamines. 8) A composition comprising at least one ketimine ofbenzylated polyamines and at least one epoxy resin.